Beneath most sinks the plumbing leading to the hot and cold water supplies is roughed out in the form of stub pipes projecting perpendicularly from the wall beneath the sink. These pipes are connected to the faucets of the sink by what are known as angle valves threaded onto the stub pipes and connector tubes leading from the angle valve up to the faucet fitting.
Typically the angle valves utilize a frictional connector to engage the connector tube comprising a compression nut which expands a resilient bushing when tightened to grip the inserted connector tube. The connector tube traditionally was made of copper tubing, which could be manually bent to the geometry needed to connect the valves with the faucets.
Because it is somewhat difficult and time-consuming to bend the conventional copper tubing to the proper configuration recently a flexible connector tube has been brought into virtually universal use. This tube has a large length which is provided with helical convolutions making it much easier to bend and reducing the time of installation considerably. However, despite the advantage of time saving inherent in the utilization of the flexible connector tube, it is accompanied by a major drawback. Whereas while the stiff, smooth-surfaced copper tubing would remain in the slip joint at the angle valve indefinitely, the flexible connector tube has a tendency to work out of the slip joint over a period of time. This is both because the tube is more flexible and because the convolutions offer more water resistance and make the tube more susceptible to air hammer and gradual displacement of the tube due to fluid friction.
Although ordinarily a leak will develop as the tube more and more closely approaches being free of the slip joint, occasionally it pops free without previous notice. Clearly the results of this can be catastrophic, especially if the tenents are not home and the unit is in an apartment building where the unchecked water flow can damage multiple units before the situation is corrected.
However, inasmuch as the time savings are so significant in installation, and because plumbers are generally in a considerable hurry, there is no likelihood that standard copper tubing will be resumed for use in this application, and there is therefore a need for a simple means of positively locking the tube into the slip joint of the angle valve, and preferably a means which can be retrofitted onto existing units.